The Australian Transport Safety Bureau (ATSB) is Australia's national transport safety investigator. The ATSB's function is to improve safety and public confidence in the aviation, marine and rail modes of transport. The ATSB is Australia's prime agency for the independent investigation of civil aviation, rail and maritime accidents, incidents and safety deficiencies.

Media release

The ATSB has found that a Cessna 208 engine failure and forced
landing onto a lake in a remote part of south-western Tasmania last
year was due to a previous generator failure, has praised the
pilots actions in landing the aircraft and ensuring passenger
safety, and has made a number of safety recommendations to prevent
a similar failure.

The Australian Transport Safety Bureaus final investigation
report states that the aircraft, a single engine Cessna 208
floatplane was being operated on a commercial scenic flight over
rugged terrain with a pilot and 10 passengers. The occupants were
fortunate to escape unharmed, due to the pilots prompt actions in
diverting to Lake Burbury when an engine chip-detector warning
light came on. Within minutes of the warning light illuminating,
the engine failed completely and the pilot was able to conduct a
forced landing onto the lake. The aircraft ended up on a mud bank
on the edge of the lake and the occupants were able to walk away
unharmed.

A previous generator failure led to electrical discharge damage
(EDD) to the engine, resulting in its failure in-flight. EDD is a
known problem with the Pratt and Whitney Canada PT-6 series
turbo-prop engines fitted to this aircraft type. The ATSB has
investigated similar events in Australia previously and the ATSB
report cites 43 similar events reported worldwide since 1992. Some
of these events have also been investigated by the US National
Transportation Safety Board.

As a result of the ATSB investigation into this serious
incident, a number of safety actions have been implemented by the
aircraft and engine manufacturers as well as Australias Civil
Aviation Safety Authority (CASA). CASA has advised the ATSB that it
will issue mandatory aircraft maintenance instructions and
Airworthiness Bulletins to reduce the possibility of EDD occurring
and will highlight the issue to the Australian aviation industry
through its Flight Safety Australia magazine.

While the safety actions of all parties are to be commended, the
ATSB remains concerned that there remain safety issues that need to
be addressed to eliminate the possibility of EDD events leading to
engine failures of this engine type. The ATSB final report
therefore contains a number of safety recommendations to the
aircraft and engine manufacturer, the Canadian and US airworthiness
authorities, Transport Canada and the Federal Aviation
Administration and CASA.

Copies of the report can be downloaded from the ATSBs internet
site at www.atsb.gov.au